Medium-resolution spectrum of the exoplanet HIP 65426 b
Medium-resolution integral-field spectrographs (IFS) coupled with adaptive-optics such as Keck/OSIRIS, VLT/MUSE, or SINFONI are appearing as a new avenue for enhancing the detection and characterization capabilities of young, gas giant exoplanets at large heliocentric distances ( >5 au). We analyzed K-band VLT/SINFONI medium-resolution (R-lambda similar to 5577) observations of the young giant exoplanet HIP 65426 b. Our dedicated IFS data analysis toolkit (TExTRIS) optimized the cube building, star registration, and allowed for the extraction of the planet spectrum. A Bayesian inference with the nested sampling algorithm coupled with the self-consistent forward atmospheric models BT-SETTL15 and Exo-REM using the ForMoSA tool yields T-eff = 1560 +/- 100 K, log(g) = 20 au) by core accretion (CA hereafter). However, a formation by gravitational instability (GI hereafter) cannot be ruled out. The metallicity is compatible with the bulk enrichment of massive Jovian planets from the Bern planet population models. Finally, we measure a radial velocity of 26 +/- 15 km s(-1) compatible with our revised measurement on the star. This is the fourth imaged exoplanet for which a radial velocity can be evaluated, illustrating the potential of such observations for assessing the coevolution of imaged systems belonging to star forming regions, such as HIP 65426. ; Programme National de Planetologie through project grant "ISEP" French National Research Agency (ANR) European Commission ANR-14-CE33-0018 French Chilean Lab for Astronomy (FCLA) UMI-3886 European Research Council (ERC) 757561 Aparece en contenido como:European Research Council (ERC) under the European Union Swiss National Science Foundation (SNSF) P400P2_186765 German Research Foundation (DFG) KU 2849/7-1 Aparece en contenido como:DFG priority program SPP 1992 "Exploring the Diversity of Extrasolar Planets" Swiss National Science Foundation (SNSF) European Commission BSSGI0_155816 "Programme National de Physique Stellaire" (PNPS) "Programme National de Planetologie" of CNRS/INSU, France Programme National de Planetologie through project grant "EXO-SPEC" ; Versión publicada - versión final del editor